1. Field of the Invention
This invention relates to electrospinning. More specifically, the invention is a method and system for aligning fibers for the controlled placement thereof during an electrospinning process using an elliptical electric field to guide fiber deposition.
2. Description of the Related Art
Electrospinning is a polymer manufacturing process that has been revived over the past decade in order to produce micro and nano fibers as well as resulting fiber groups (or mats as they are known) with properties that can be tailored to specific applications by controlling fiber diameter and mat porosity. The individual fibers are formed by applying a high electrostatic field to a polymer solution that carries a charge sufficient to attract the solution to a grounded source. Parameters that determine fiber formation include solution viscosity, polymer/solvent interaction, surface tension, applied voltage, distance between the spinneret and collector, and the conductivity of the solution.
Typically, only non-woven mats can be produced during this process due to splaying of the fibers and jet instability of the polymer expelled from the spinneret. These non-woven mats can be used as scaffolds for tissue engineering, wound dressings, clothing, filters, and membranes. While non-woven mats have proven to be useful for a variety of applications, controlling fiber alignment in the mat is a desirable characteristic to expand the applications of electrospun materials. Particularly for the case of tissue engineering scaffolds, the control of fiber distribution, fiber alignment, and porosity of the scaffold are crucial for the success of any scaffold. Current manufacturing techniques are limited by erratic polymer whipping that often produces dense nanofiber mats, which cannot support cell infiltration or cell alignment.